Reduced wiring and the resulting lower susceptibility to faults have ensured the present day success of distributed I/O in process automation. Input and output modules (remote I/O stations) are located in the vicinity of associated sensors and actuators. These are no longer individually connected to the controller, but rather through distributed process I/Os. The connection between distributed input and output modules (slaves) and central controllers (masters) is made through established bus systems such as PROFIBUS or PROFINET.

SIMATIC PCS 7 offers numerous options for connecting I/Os as well as for sending and receiving process signals via sensors and actuators: